Piston expander



D. M. SMITH PISTON EXPANDER Aug. 27, 1940.

Filed Jan. 6, 1940 FIGI.

' IN VENTO/:

rammed Aug. 27, 1940` UNITED STATES PATENT OFFICE McQuay-Norris Manufacturing Company, Louis. Mo., a corporation of Delaware Application January 6,

5Claiml.

My invention relates to piston expanders and more particularly to expanders designed to increase the diameter of the resilient split skirt of an internal combustion engine piston.

As fully set forth in my co-pending application Serial number 312,746 for Piston expanders led January 6, 1940, expanders of this type as heretofore used have had a major deficiency of structure in that such expanders were not adjustable. That is, for a given expander only a definite expansive force could be exerted to expand a piston skirt of a given type and diameter. This lack of adjustability in expanders heretofore used made it necessary for manufacturers and distributors to make and stock many different sizes of expanders because a separate expander of a definite size was needed for each different piston. Also, an expander of given size would not expand to the same degree two different pistons of the same size -and type because of varying stiffness and texture of the metal from which the pistons were formed. Furthermore, the pistons in internal combustion engines often wear in different ways so that there are different clearances betwen the pistons and their cylinders in the same motor after use. As stated above, since the expanders hertofore used were not adjustable all of the pistons in the motor were expanded or increased in diameter to the same degree and a proper expansive force for one often would not suilice for another piston in the` motor.

In my co-pending application. I have disclosed and claimed one form of adjustable expander and the objects of this invention are to provide a piston expander of a different type which will be adjustable; to provide an expander in the use of which the expensive force exerted outwardly against the piston skirt may be regulated and controlled; and to provide an expander which will be efllcacious in use, simple in design and easy to install.

My invention in its broadest form includes an expander comprising a pair of legs movable relative to one another and means for moving these legs and maintaining them in predetermined adjusted position. It should be understood that expanders embodying this invention may be made in numerous shapes, arrangements and forms. However, in the accompanying drawing wherein similar characters are used to designate similar parts, I have shown two embodiments only of my invention. In this drawing, Fig. 1 is a view of a piston with an expander embodying my invention installed therein; Fig.

1940, semi No. 312,141 (ci. sos-iz) 2 is a top view of this expander: Fig. 3 is a section on line 3 3 of Fig. 1, showing the means for adjusting the parts to create varying expansive forces; Fig. 4 shows the devicel of Fig. 2 in y elevation; Fig. 5 shows a modified form of expander in place in a piston; and Fig. 6 is a top view of the expander as shown in Fig. 5.

Referring to the figures and more particularly to the device shown in Figs. 1 to 4, inclusive, the piston in which the expander is mounted includes the usual head A having a ring belt B and a resilient skirt C axially slotted as at D and separated throughout most of its circumference from the head by circumferentially extending slots D. The piston has bosses E in which is mounted a pin to support the usual connectin rod.

I'his expander is formed of spring wire of substantial diameter and has a .pair of legs F and G, each formed of a yloop of wire as shown in Figs. 2 and 3. At their upper ends the legs F and G terminate in integral straight portions H and J, respectively. Secured to the ends of the portions H is a bar K and secured to the ends of the portions J is a bar L. The portions J extend through and slidably engage suitable apertures in the bar` K and the portions H extend through and slidably engage similar apertures in the bar L.

It will be seen that as the bars K and L are moved towards one another the distance between the legs F and G will be increased and, when the expander is in place in a piston, as shown in Fig. 1, if these bars are maintained in predetermined adjusted position the expansive force of the lower ends of the legs F and G in engagement with the inner surface of the skirt may be regulated to increase the diameter of the skirt to varying degrees. Preferably, the expander is arranged in a piston so that the lower ends of the legs F and G engage the skirt at diametrically opposite points about ninety degrees from the bosses E. Also, I prefer that the legs be of proper length as shown in Fig. 1 so that the skirt is engaged at a point' slightly below the bosses because I have found that such engagement makes for most effective expansion of the skirt of the type shown.

As stated above, an expander embodying my invention includes means for moving the legs thereof relative to one another and for maintaining the legs in predetermined adjusted position. In the type now being described such means comprises a shaft M which is threaded throughout a portion of its length and is adapted to freely move in a hole in the bar K, but is threaded in the boss N formed in the bar L.

A stop is provided on the shaft M to engage the bar K and in this embodiment such stop is formed by a nut O threaded on the shaft and turned to be positioned at the end of the threaded portion thereof. The shaft M may extend through diametrically registering holes Q in the head of the piston and such holes are preferably formed at the bottom of the lower ring groove. Also, preferably, when the expander is made the shaft M is bent at the unthreaded end thereof to form a small crank handle P to facilitate rotation of the shaft for the purposes explained below.

The use of this type of expander is as follows: The assembly comprising the legs F and G and their carried bars K and L is inserted in the piston. The shaft M is then slipped through one of the diametrically registering holes Q in the plston head and the nut O is turned thereon. 'I'he threaded end of the shaft is then inserted through the hole in the bar K, is turned through the threaded opening in the boss N and is entered into the other hole Q. As rotation of the shaft M is continued by the crank P the nut O will engage the outer side face of the bar K and rotation of the shaft will move the bars K and L towards one another. 'I'his action will separate the legs F and G and a firm expansive force will be exerted against the skirt to increase the diameter thereof. When the piston skirt has been expanded to the proper degree to t within the cylinder in which it is to be used the ends of the shaft M are cut off ush with the bottom wall of the ring groove or other `portion of the piston head through which the shaft extends.

The expander will then be held in place iirmly in the piston and the piston may be inserted in its cylinder to have a proper effective operative t. I have found if the legs F and G are moved apart to an extent to exert sufficient expansive force on the piston skirt the parts H and J and the shaft M will be somewhat bowed and the resultant tension will prevent flutter or vibrations of these portions of the expander. Also, if necessary, the shaft M may be threaded throughout its entire length and a lock nut may be inserted at each end thereof to be turned outwardly against the inner surface of the piston head whereby the shaft will be locked in plaee in the diametrically opposed openings in the head through which the shaft extends.

The embodiment shown in Figs. 5 and 6 is similar in operation to the embodiment described above except that the legs F' and G' are formed of fiat spring metal instead of spring wire. At their upper ends such iiat legs terminate in straight portions H and J', respectively, and such portions are fixed to and have slidable engagement with the bars L' and K' as described relative to the other embodiment. The legs F' and G' have enlarged openings R therein to accommodate a shaft M which may terminate in a crank handle P similar to the embodiment described above. 'Ihis shaft has a nut O' to bear against the bar K' and is threaded in the bar amaoos L so that rotation of the shaft will move the bars L' and K' together whereby an expansive force will be exerted outwardly through the legs F' and G' against the inner surface of the piston skirt to expand it to the proper diameter. 5

The use of this embodiment of my invention will-be understood from the description of the operation of the embodiment shown above in Figs. 1 to 4, inclusive.

As stated above,'diiferent embodiments of my 10 invention may be made in various shapes and forms without deviating from the invention as included in the appended claims. For instance, the adjustable legs of the device may be connected Lat their lower ends to steady them and l5 to give added strength to the expander. Also, an adjustable expander embodying my invention maybe held in the piston by any of the expedients heretofore used and I do not intend to limit myself to the method of attachment shown andi described herein. i

What I claim as new and desire to secure by Letters Patent, is:

1. A piston skirt expander comprising a pair of legs movable relative to one another and means for moving said legs and maintaining said legs in predetermined adjusted position whereby the expansive force exerted by said expander in a piston may be varied.

2. A piston skirt expander comprising a pair of legs movable relative to one another and terminating in parallel straight portions, means for moving said straight portions to cause said legs to be moved to exert'an outward expansive force and means for maintaining said legs in prede- 36 termined adjusted position.

3. A piston skirt expander comprising a pair of legs movable relative to one another and terminating in parallel straight portions, means for moving said straight portions to cause said legs to be moved away from one another and to exert an outward expansive force against the skirt of a piston in which said expander is used and means for maintaining said legs in predetermined adjusted position.

4. A piston skirt expander comprising a pair of legs movable relative to one another and terminating in parallel straight portions, each of said portions having a bar xed thereto and having sliding engagement with the bar fixed to the other of said portions, and means for moving said bars towards or away from one another whereby said legs will be moved relative to one another and the outward expansive force exerted by said legs may be adjusted.

5. A piston skirt expander comprising a pair of legs movable relative to one another and terminating in parallel straight portions, each of said portions having a bar fixed thereto and having sliding engagement with the bar iixed to w the other of said portions, means for moving said bars towards or away from one another whereby said legs will be moved relative to one another and the outward expansive force exerted by said legs may be adjusted, and means for maintain- 05 ing said legs in predermined adjusted position.

DALLAS M. SMITH. 

